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Stock-Based Compensation - Stock Option Activity (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2016
Dec. 31, 2015
Number of Stock Options:    
Outstanding, beginning of period (in shares) 414,769  
Exercised (in shares) (22,750)  
Outstanding, end of period (in shares) 392,019 414,769
Exercisable (in shares) 336,187  
Weighted Average Exercise Price:    
Outstanding, weighted average exercise price, beginning of period (in USD per share) $ 19.07  
Exercised, weighted average exercise price (in USD per share) 15.46  
Outstanding, weighted average exercise price, end of period (in USD per share) 19.28 $ 19.07
Exercisable, weighted average exercise price (in USD per share) $ 18.22  
Options, Weighted Average Remaining Contractual Term:    
Outstanding, weighted average remaining contractual life 5 years 5 days 5 years 29 days
Exercisable, weighted average remaining contractual life 4 years 4 months 25 days  
Options, Intrinsic Value:    
Outstanding, aggregate intrinsic value $ 1,468 $ 1,814
Exercised, aggregate intrinsic value 137  
Exercisable, aggregate intrinsic value $ 1,468